The traditional toilet tank is applied with water level difference of the tank and the toilet to generate pressure to make the flushing water with high speed to clean the toilet. However, when the water level difference is little and the flushing is weak, it needs more water to clean the toilet. So there is pressure type toilet tank in conventional technology. As figured in FIG. 1, the pressure type toilet tank is applied with a closed tank 1′, which is stored with some air when it is tanking in water, the air inside the tank is compressed by the water pressure of the water supply pipe, the dynamic of the compression air and the water pressure can release the energy when the tank is flushing by the control of the flush valve 2′, making water discharged quickly to the toilet from the outlet of the tank 1′ to flush powerfully, thus saving water. Experience has proved that the flush effect and the water saving effect of the pressure type toilet tank of conventional technology are better than the traditional toilet tank which is flushing by the force of the water gravity.
The tank of the pressure type toilet tank of conventional technology is made of metal, so there are disadvantages that it costs high and it is out of step with energy-saving benefit, thus making it difficult to widely use. So that some manufactories use reinforce plastic to replace the expensive metal to make toilet tank. With mature manufacture technology, low cost and high reliably, and with the cooperation of the pressure control system (the pressure maintaining valve 3′ in FIG. 1) and the safety device (the safety valve 4′ in FIG. 1), this kind of tank is widely manufactured to be provided in the market. However, though this kind of pressure type toilet tank is with well flush effect, energy saving benefit, low cost and popular in the market, it is a security threat. Due to the high water supply pressure and bad manufacturing of the products, if the tank becomes fatigue or the safety device is broken, the inside pressure of the tank may sharply increase and it is hard to release, causing exploding under the strong pressure, the ceramic housing of the tank may be broken to sharp pieces, causing personal injury or property damage.